Port B acting as Egress
During the congestion, [traffic pump on priorities 3 and 4 from PORT A and PORT C is at full line rate], PORT A and C send out the PFCs
to rate the traffic limit. Egress drops are not observed on Port B since traffic flow on priorities is mapped to loss less queues.
Port B acting as Ingress
If the traffic congestion is on PORT B , Egress DROP is on PORT A or C, as the PFC is not enabled on PORT B.
Refer the following configuration for queue to dot1p mapping:
Dell(conf)#do show qos dot1p-queue-mapping
Dot1p Priority : 0 1 2 3 4 5 6 7 -> On ingress interfaces[Port A and C] we used the
PFC on priority level.
Queue : 0 0 0 1 2 3 3 3 -> On Egress interface[Port B] we used no-drop queues.
Lossless traffic egresses out the no-drop queues. Ingress 802.1p traffic from PFC-enabled peers is automatically mapped to the no-drop
egress queues.
When configuring lossless queues on a port interface, consider the following points:
•
By default, no lossless queues are configured on a port.
•
A limit of two lossless queues is supported on a port. If the number of lossless queues configured exceeds the maximum supported limit
per port (two), an error message is displayed. Reconfigure the value to a smaller number of queues.
•
If you configure lossless queues on an interface that already has a DCB map with PFC enabled (
pfc on
), an error message is displayed.
Table 18. Configuring Lossless Queues on a Port Interface
Step
Task
Command
Command Mode
1
Enter INTERFACE Configuration mode.
interface
{
tengigabitEthernet
slot
/
port
[
/subport
] |
fortygigabitEthernet
slot
/
port
}
CONFIGURATION
2
Open a DCB map and enter DCB map configuration mode.
dcb-map
name
INTERFACE
3
Disable PFC.
no pfc mode on
DCB MAP
4
Return to interface configuration mode.
exit
DCB MAP
5
Apply the DCB map, created to disable the PFC operation,
on the interface
dcb-map
{
name
|
default
}
INTERFACE
6
Configure the port queues that still function as no-drop
queues for lossless traffic. For the dot1p-queue
assignments.
The maximum number of lossless queues globally supported
on a port is 2.
You cannot configure PFC no-drop queues on an interface
on which a DCB map with PFC enabled has been applied,
or which is already configured for PFC using the
pfc
priority
command.
Range: 0-3. Separate queue values with a comma; specify a
priority range with a dash; for example: pfc no-drop queues
pfc no-drop
queues
queue-range
INTERFACE
Data Center Bridging (DCB)
263
Содержание S4048T-ON
Страница 1: ...Dell Configuration Guide for the S4048 ON System 9 11 2 1 ...
Страница 148: ...Figure 10 BFD Three Way Handshake State Changes 148 Bidirectional Forwarding Detection BFD ...
Страница 251: ...Dell Control Plane Policing CoPP 251 ...
Страница 363: ... RPM Synchronization GARP VLAN Registration Protocol GVRP 363 ...
Страница 511: ...Figure 64 Inspecting the LAG Configuration Link Aggregation Control Protocol LACP 511 ...
Страница 512: ...Figure 65 Inspecting Configuration of LAG 10 on ALPHA 512 Link Aggregation Control Protocol LACP ...
Страница 515: ...Figure 67 Inspecting a LAG Port on BRAVO Using the show interface Command Link Aggregation Control Protocol LACP 515 ...
Страница 516: ...Figure 68 Inspecting LAG 10 Using the show interfaces port channel Command 516 Link Aggregation Control Protocol LACP ...
Страница 558: ...Figure 84 Configuring Interfaces for MSDP 558 Multicast Source Discovery Protocol MSDP ...
Страница 559: ...Figure 85 Configuring OSPF and BGP for MSDP Multicast Source Discovery Protocol MSDP 559 ...
Страница 560: ...Figure 86 Configuring PIM in Multiple Routing Domains 560 Multicast Source Discovery Protocol MSDP ...
Страница 564: ...Figure 88 MSDP Default Peer Scenario 2 564 Multicast Source Discovery Protocol MSDP ...
Страница 565: ...Figure 89 MSDP Default Peer Scenario 3 Multicast Source Discovery Protocol MSDP 565 ...
Страница 729: ...protocol spanning tree pvst no disable vlan 300 bridge priority 4096 Per VLAN Spanning Tree Plus PVST 729 ...
Страница 841: ...Figure 115 Single and Double Tag TPID Match Service Provider Bridging 841 ...
Страница 842: ...Figure 116 Single and Double Tag First byte TPID Match 842 Service Provider Bridging ...